which a given process with PID belongs?

Which two commands can be used to find the cgroup to which a given process with PID belongs?

A.
egget -a | grep PID

B.
ps -o cgroup | grep PID

C.
cat /proc/PID/cgroup

D.
Iscgroup | grep PID

Explanation:
Reference:https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Resource_Management_Guide/